Mybatis一对一结果映射

落日映苍穹つ 2023-07-03 06:04 120阅读 0赞

# 目录结构 #

![目录结构][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70]

# 创建数据库相应的表 #

**一个账户对应一个用户**  
**accout**

CREATE TABLE `account` (
      `aid` int(11) NOT NULL AUTO_INCREMENT,
      `accountname` varchar(20) DEFAULT NULL,
      `money` float(10,2) DEFAULT NULL,
      `userId` int(11) DEFAULT NULL,
      PRIMARY KEY (`aid`),
      KEY `userId` (`userId`),
      CONSTRAINT `account_ibfk_1` FOREIGN KEY (`userId`) REFERENCES `user` (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

**user**

CREATE TABLE `user` (
      `id` int(11) NOT NULL AUTO_INCREMENT,
      `username` varchar(20) DEFAULT NULL,
      `PASSWORD` varchar(20) DEFAULT NULL,
      `sex` varchar(2) DEFAULT NULL,
      `birthday` date DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8;

# domain 实体类 #

Account

package com.william.domain;
    
    /**
     * @author ：lijunxuan
     * @date ：Created in 2020/2/2  20:35
     * @description ：
     * @version: 1.0
     */
    public class Account {
        Integer aid;
        String accountname;
        Float money;
        Integer userId;
        User user;
    
        @Override
        public String toString() {
            return "Account{" +
                    "aid=" + aid +
                    ", accountname='" + accountname + '\'' +
                    ", money=" + money +
                    ", userId=" + userId +
                    ", user=" + user +
                    '}';
        }
    
        public Integer getAid() {
            return aid;
        }
    
        public void setAid(Integer aid) {
            this.aid = aid;
        }
    
        public String getAccountname() {
            return accountname;
        }
    
        public void setAccountname(String accountname) {
            this.accountname = accountname;
        }
    
        public Float getMoney() {
            return money;
        }
    
        public void setMoney(Float money) {
            this.money = money;
        }
    
        public Integer getUserId() {
            return userId;
        }
    
        public void setUserId(Integer userId) {
            this.userId = userId;
        }
    
        public User getUser() {
            return user;
        }
    
        public void setUser(User user) {
            this.user = user;
        }
    }

User

package com.william.domain;
    
    /**
     * @author ：lijunxuan
     * @date ：Created in 2020/2/2  20:37
     * @description ：
     * @version: 1.0
     */
    public class User {
        Integer id;
        String username;
        String PASSWORD;
        String sex;
        String birthday;
    
        @Override
        public String toString() {
            return "User{" +
                    "id=" + id +
                    ", username='" + username + '\'' +
                    ", PASSWORD='" + PASSWORD + '\'' +
                    ", sex='" + sex + '\'' +
                    ", birthday='" + birthday + '\'' +
                    '}';
        }
    
        public Integer getId() {
            return id;
        }
    
        public void setId(Integer id) {
            this.id = id;
        }
    
        public String getUsername() {
            return username;
        }
    
        public void setUsername(String username) {
            this.username = username;
        }
    
        public String getPASSWORD() {
            return PASSWORD;
        }
    
        public void setPASSWORD(String PASSWORD) {
            this.PASSWORD = PASSWORD;
        }
    
        public String getSex() {
            return sex;
        }
    
        public void setSex(String sex) {
            this.sex = sex;
        }
    
        public String getBirthday() {
            return birthday;
        }
    
        public void setBirthday(String birthday) {
            this.birthday = birthday;
        }
    }

# mapper Dao #

package com.william.mapper;
    
    import com.william.domain.Account;
    import com.william.domain.QueryVo;
    import com.william.domain.Usert;
    import org.apache.ibatis.annotations.Param;
    
    import java.util.HashMap;
    import java.util.List;
    
    public interface Usermapper {
        List<Account> findByhaha();
    }

# mapper.xml 映射文件 #

## 可以有两种配置方式： ##

### 方式一： ###

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.william.mapper.Usermapper">
        <resultMap id="accoutMap" type="account">
            <id property="aid" column="aid"></id>
            <result property="accountname" column="accountname"></result>
            <result property="money" column="money"></result>
            <result property="userId" column="userId"></result>
            <result property="user.id" column="id"></result>
            <result property="user.username" column="username"></result>
            <result property="user.PASSWORD" column="PASSWORD"></result>
            <result property="user.sex" column="sex"></result>
            <result property="user.birthday" column="birthday"></result>
        </resultMap>
        <select id="findByhaha" resultMap="accoutMap">
            select * from account a ,user u where a.userId=u.id;
        </select>
    </mapper>

### 方式二：使用association标签 ###

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE mapper
            PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
    <mapper namespace="com.william.dao.AccountDao">
        <resultMap id="resultMap" type="account">
            <id column="aid" property="aid"></id>
            <result column="accountname" property="accountname"></result>
            <result column="money" property="money"></result>
            <result column="userId" property="userId"></result>
            
            
            <association property="user" javaType="user">
              <id column="id" property="id"></id>
              <result column="username" property="username"></result>
                <result column="PASSWORD" property="PASSWORD"></result>
                <result column="sex" property="sex"></result>
                <result column="birthday" property="birthday"></result>
            </association>
        </resultMap>
        <select id="findAll" resultMap="resultMap">
            select * from account a,user u where a.userId=u.id;
        </select>
    </mapper>

# 配置文件 #

## **1.db.properties** 数据库配置文件 ##

jdbc.driver=com.mysql.jdbc.Driver
    jdbc.url=jdbc:mysql://localhost:3306/web02
    jdbc.user=root
    jdbc.password=root

## **2.log4j.properties日志文件** ##

# Set root category priority to INFO and its only appender to CONSOLE.
    #log4j.rootCategory=INFO, CONSOLE            debug   info   warn error fatal
    log4j.rootCategory=debug, CONSOLE, LOGFILE, info
    
    # Set the enterprise logger category to FATAL and its only appender to CONSOLE.
    log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE
    
    # CONSOLE is set to be a ConsoleAppender using a PatternLayout.
    log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
    log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
    log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n
    
    # LOGFILE is set to be a File appender using a PatternLayout.
    log4j.appender.LOGFILE=org.apache.log4j.FileAppender
    log4j.appender.LOGFILE.File=d:\axis.log
    log4j.appender.LOGFILE.Append=true
    log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
    log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

## 3.核心配置文件Mybatis-config.xml ##

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE configuration
            PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
            "http://mybatis.org/dtd/mybatis-3-config.dtd">
    <configuration>
        <properties resource="db.properties"></properties>
        <typeAliases>
            <package name="com.william.domain"></package>
        </typeAliases>
        <environments default="develoment">
            <environment id="develoment">
                <transactionManager type="JDBC"/>
                <dataSource type="POOLED">
                    <property name="driver" value="${jdbc.driver}"></property>
                    <property name="url" value="${jdbc.url}"></property>
                    <property name="username" value="${jdbc.user}"></property>
                    <property name="password" value="${jdbc.password}"></property>
                </dataSource>
            </environment>
        </environments>
        <mappers>
            
            <package name="com.william.mapper"></package>
        </mappers>
    </configuration>

# test测试类 #

package com.william.test;
    
    import com.william.domain.Account;
    import com.william.domain.QueryVo;
    import com.william.domain.Usert;
    import com.william.mapper.Usermapper;
    import org.apache.ibatis.io.Resources;
    import org.apache.ibatis.session.SqlSession;
    import org.apache.ibatis.session.SqlSessionFactory;
    import org.apache.ibatis.session.SqlSessionFactoryBuilder;
    import org.junit.Test;
    
    import java.io.IOException;
    import java.util.HashMap;
    import java.util.List;
    
    /**
     * @author ：lijunxuan
     * @date ：Created in 2020/2/2  13:28
     * @description ：
     * @version: 1.0
     */
    public class TestMyBatis {
        /**
         * 查询所有的账户相同的
         */
        @Test
        public void selectAll(){
            try {
                SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("Mybatis-config.xml"));
                SqlSession sqlSession = sqlSessionFactory.openSession(true);
                Usermapper mapper = sqlSession.getMapper(Usermapper.class);
                List<Account> list = mapper.findByhaha();
                for (Account account : list) {
                    System.out.println(account.getAid());
                    System.out.println(account);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

# 测试结果 #

![测试结果][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 1]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200202211408595.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200202211328709.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NpbmF0XzM5MTc5OTkz,size_16,color_FFFFFF,t_70